The folks at the Los Angeles Times take their photo-journalism seriously:
The primary subject of the photo was a British soldier directing Iraqi civilians to take cover from Iraqi fire on the outskirts of Basra. After publication, it was noticed that several civilians in the background appear twice. The photographer, Brian Walski, reached by telephone in southern Iraq, acknowledged that he had used his computer to combine elements of two photographs, taken moments apart, in order to improve the composition.
Times policy forbids altering the content of news photographs. Because of the violation, Walski, a Times photographer since 1998, has been dismissed from the staff.
The explanation linked to above shows both of the original photos prior to the editing. The temptation to improve on reality is understandable, but can not be tolerated if the integrity of the press is to be maintained.